A2A Simulations BONANZA ACCU-SIM V35B, Manual

Page: 49 / 112

www.a2asimulations.com ACCU-SIM V35B BONANZA ::: A2A SIMULATIONS
49
FOR SIMULATION USE ONLY
WEAK
STRONG
Cold air is denser
and so provides
more oxygen to
your engine. More
oxygen means
more power.
Just before the air enters the combustion chamber it
is mixed with fuel. Think of it as an air / fuel mist.
When you push the throttle forward, you are opening
a valve allowing your engine to suck in more fuel / air
mixture.
T
he combustion engine is basically an
air pump. It creates power by pull-
ing in an air / fuel mixture, igniting it,
and turning the explosion into usable
power. The explosion pushes a piston
down that turns a crankshaft. As the
pistons run up and down with con-
trolled explosions, the crankshaft spins. For an automobile,
the spinning crankshaft is connected to a transmission (with
gears) that is connected to a driveshaft, which is then con-
nected to the wheels. This is literally “putting power to the
pavement.” For an aircraft, the crankshaft is connected to
a propeller shaft and the power comes when that spinning
propeller takes a bite of the air and pulls the aircraft forward.
The main difference between an engine designed for an
automobile and one designed for an aircraft is the aircraft
engine will have to produce power up high where the air
is thin. To function better in that high, thin air, a super-
charger can be installed to push more air into the engine.
OVERVIEW OF HOW THE ENGINE
WORKS AND CREATES POWER
Fire needs air. We need air. Engines need air. Engines are
just like us as – they need oxygen to work. Why? Because
fire needs oxygen to burn. If you cover a fire, it goes out
because you starved it of oxygen. If you have ever used a
wood stove or fireplace, you know when you open the vent
to allow more air to come in, the fire will burn more. The
same principle applies to an engine. Think of an engine like
a fire that will burn as hot and fast as you let it.
Look at these four images on the left and you will under-
stand basically how an engine operates.
The piston pulls in the fuel / air mixture, then compresses
the mixture on its way back up.
The spark plug ignites the compressed air / fuel mixture,
driving the piston down (power), then on its way back up,
the burned mixture is forced out the exhaust.
AIR TEMPERATURE
Have you ever noticed that your car engine runs smoother
and stronger in the cold weather? This is because cold air is
denser than hot air and has more oxygen. Hotter air means
less power.
MIXTURE
Just before the air enters the combustion chamber it is
mixed with fuel. Think of it as an air / fuel mist.
A general rule is a 0.08% fuel to air ratio will produce the
most power. 0.08% is less than 1%, meaning for every 100
parts of air, there is just less than 1 part fuel. The best eco-
nomical mixture is 0.0625%.
Why not just use the most economical mixture all the time?
Because a leaner mixture means a hotter running engine.
Fuel actually acts as an engine coolant, so the richer the
mixture, the cooler the engine will run.
However, since the engine at high power will be nearing
its maximum acceptable temperature, you would use your